This paper reports on an experiment which tested how sound symbolic knowledge is acquired by Japanese children. The empirical focus is associations between certain types of sounds and certain types of shapes. Köhler's (1947) classic study has revealed that the nonce word takete is more likely to be associated with angular shapes, hereas the nonce word maluma is more likely to be associated with round shapes. Later studies generalized this finding in such a way that obstruents are associated with angular shapes, whereas sonorants are associated with round shapes. It remains to be examined, however, how the knowledge of these sound symbolic associations is acquired. The present study thus employs the preferential looking paradigm using eye-tracking technology to examine how the knowledge of these sound symbolic associations is acquired by Japanese speakers. The results show that the sound-symbolic associations at issue hold not only among adult Japanese speakers, but also among 6-year-old children who have not attended elementary school, and even more strikingly, among 2/3-year-old children.